Children and adults minimise activated muscle volume by selecting gait parameters that balance gross mechanical power and work demands

Terrestrial locomotion on legs is energetically expensive. Compared with cycling, or with locomotion in swimming or flying animals, walking and running are highly uneconomical. Legged gaits that minimise mechanical work have previously been identified and broadly match walking and running at appropriate speeds. Furthermore, the ‘cost of muscle force’ approaches are effective in relating locomotion kinetics to metabolic cost. However, few accounts have been made for why animals deviate from either work-minimising or muscle-force-minimising strategies. Also, there is no current mechanistic account for the scaling of locomotion kinetics with animal size and speed. Here, we report measurements of ground reaction forces in walking children and adult humans, and their stance durations during running. We find that many aspects of gait kinetics and kinematics scale with speed and size in a manner that is consistent with minimising muscle activation required for the more demanding between mechanical work and power: spreading the duration of muscle action reduces activation requirements for power, at the cost of greater work demands. Mechanical work is relatively more demanding for larger bipeds – adult humans – accounting for their symmetrical M-shaped vertical force traces in walking, and relatively brief stance durations in running compared with smaller bipeds – children. The gaits of small children, and the greater deviation of their mechanics from work-minimising strategies, may be understood as appropriate for their scale, not merely as immature, incompletely developed and energetically sub-optimal versions of adult gaits

Proprioceptive Coupling within Motor Neurons Drives C. Elegans Forward Locomotion

Locomotion requires coordinated motor activity throughout an animal’s body. In both vertebrates and invertebrates, chains of coupled central pattern generators (CPGs) are commonly evoked to explain local rhythmic behaviors. In C. elegans, we report that proprioception within the motor circuit is responsible for propagating and coordinating rhythmic undulatory waves from head to tail during forward movement. Proprioceptive coupling between adjacent body regions transduces rhythmic movement initiated near the head into bending waves driven along the body by a chain of reflexes. Using optogenetics and calcium imaging to manipulate and monitor motor circuit activity of moving C. elegans held in microfluidic devices, we found that the B-type cholinergic motor neurons transduce the proprioceptive signal. In C. elegans, a sensorimotor feedback loop operating within a specific type of motor neuron both drives and organizes body movement.Chemistry and Chemical BiologyPhysic

The scaling or ontogeny of human gait kinetics and walk-run transition: The implications of work vs. peak power minimization

A simple model is developed to find vertical force profiles and stance durations that minimize either limb mechanical work or peak power demands during bipedal locomotion. The model predicts that work minimization is achieved with a symmetrical vertical force profile, consistent with previous models and observations of adult humans, and data for 487 participants (predominantly 11–18 years old) required to walk at a range of speeds at a Science Fair. Work minimization also predicts the discrete walk-run transition, familiar for adult humans. In contrast, modeled peak limb mechanical power demands are minimized with an early skew in vertical ground reaction force that increases with speed, and stance durations that decrease steadily with speed across the work minimizing walk-run transition speed. The peak power minimization model therefore predicts a continuous walk-run gait transition that is quantitatively consistent with measurements of younger children (1.1–4.7 years) required to locomote at a range of speeds but free to select their own gaits

The locomotor kinematics and ground reaction forces of walking giraffes.

Giraffes (Giraffa camelopardalis Linnaeus 1758) possess specialised anatomy. Their disproportionately elongate limbs and neck confer recognised feeding advantages, but little is known about how their morphology affects locomotor function. In this study, we examined the stride parameters and ground reaction forces from three adult giraffes in a zoological park, across a range of walking speeds. The patterns of GRFs during walking indicate that giraffes, similar to other mammalian quadrupeds, maintain a forelimb-biased weight distribution. The angular excursion of the neck has functional links with locomotor dynamics in giraffes, and was exaggerated at faster speeds. The horizontal accelerations of the neck and trunk were out of phase, compared with the vertical accelerations which were intermediate between in and out of phase. Despite possessing specialised morphology, giraffes’ stride parameters were broadly predicted from dynamic similarity, facilitating the use of other quadrupedal locomotion models to generate testable hypotheses in giraffes

Analogon: Of a World Already Animated

Films, and perhaps especially animated films, are ways of thinking. In their own ways, and beyond any intention of human filmmakers, films think (Frampton 2006). Animations think especially hard about movement, time and, unsurprisingly, animation: what motivates something to move. In their remarkably different ways, Muto (2007-8) and Der Lauf der Dinge (1987) undertake a radical thinking-through of change, respectively as mutation and its constituents, and the capacities of film generally and animation specifically to unhinge and re-articulate classifications of human, environmental and technological life. Muto is a seven-minute graphic by Italian street artist Blu filmed in stop-motion on location in Buenos Aires as the artist and his team paint, erase and redraw a series of evolving figures on the walls of the city. Der Lauf der Dinge (The Way Things Go) is a 30-minute film by Swiss artists Peter Fischli and David Weiss which documents in a series of long takes (with carefully concealed edits) a series of homemade devices which variously decompose, fall, crash and burn to produce a chain reaction of events

Aspects of feminine mythology and related pictoral imagery as source for the development of a personal sculptural iconography

The representation of the female figure in Western society has been moulded by such diverse forces as religion, economy and geography, nonetheless, certain images of the female form and representations of feminine qualities appear to be archetypal. One example is that of the Venus of Willendorf which has been recognised as a generalised image of women's fertility. This is mainly due to its formal exaggeration of, and emphasis on, the reproductive aspects of women's bodies. A second example is contained in the theories of Jungian psychologists who have recognised the feminine principle as embodied in the myths and pictorial imagery of what is known as the great goddess. They maintain that the symbols and images from these myths are similar to those in the myths, dreams and fantasies of modern individuals. Following on from these insights the first series of sculptures was aimed at examining women's experience of the reproductive aspects of their bodies in patriarchal society. Generalised images of female fertility were represented through the expressive device of exaggeration. I was concerned to express each woman's individuality by including facial details and gesture. It was also necessary to depict conventionalised elements of patriarchal society. This was achieved through a personification of bestial attributes. The ceramic medium offered many advantages, among them, its primordial qualities and its suitability for modelling and casting voluminous forms. An interest in broader aspects of femininity developed out of the study of images of the great goddess. This was facilitated by a reading of Jungian contrasexual psychology which maintains that the feminine principle is a universal psychological element specific to both men and women. The intention in the second series of sculptures was to celebrate this principle. Since it is not gender-related, it was necessary to find imagery other than that of the female figure. The feminine principle is not definable in purely physical terms since it is experienced in the conscious and unconscious mind, in fantasy, and in what is taken for reality. Abstract symbols associated with goddess mythology were recontextualised in this series and were intended to function on several layers of perception. The technique of modelling cement onto a metal armature facilitated the bold and celebratory forms chosen to celebrate the feminine principle

A Hazard Assessment and Proposed Risk Index for Art, Architecture, Archive and Artifact Protection: Case Studies for Assorted International Museums

This study proposes a hazard/risk index for environmental, technological, and social hazards that may threaten a museum or other place of cultural storage and accession. This index can be utilized and implemented to measure the risk at the locations of these storage facilities in relationship to their geologic, geographic, environmental, and social settings. A model case study of the 1966 flood of the Arno River and its impact on the city of Florence and the Uffizi Gallery was used as the index focus. From this focus an additional eleven museums and their related risk were assessed. Each index addressed a diverse range of hazards based on past frequency and magnitude. It was found that locations nearest a hazard had exceptionally high levels of risk, however more distant locations could have influences that would increase their risk to levels similar to those locations near the hazard. Locations not normally associated with a given natural hazard can be susceptible should the right conditions be met and this research identified, complied and assessed those factions found to influence natural hazard risk at these research sites

Improved viewshed modelling for estimating effects of neighboring land uses on property values

The effect of land uses on neighboring property values is of critical interest to urban planners, developers, and citizens. Property values are in part defined by built structure and lot characteristics, locational attributes (e.g., proximity to amenities and disamenities), and other features such as views from a property. The effects of these attributes can be estimated using the hedonic property valuation method. While many of these attributes are easily quantified, views are less tangible. This study attempts to develop a viewshed estimation technique that takes into account the limbing up of trees, a major limitation of viewshed estimates to date. The limbing up effect was estimated using a conditional statement on three viewsheds: ground elevation only, ground elevation plus 8 feet where there are trees, and the elevation of vegetation (LIDAR). The viewsheds areas were intersected with their land use zone (residential, institutional, agricultural, etc) as well as their land use category (pavement, building, short, or tall vegetation) and perspective was controlled for. The viewshed estimates were evaluated within econometric models, yielding some interesting results, including that increased visibility of houses and pavement reduced property values, short vegetation had a positive effect, and views of trees themselves had no significant effect. While the techniques used in this study have great potential, they were limited in their current application due to computing power. Further investigations may help overcome some of the constraints within this study and explore variations on this technique in order to generate robust viewshed estimates